Several forms of collapsible containers are known, including those of the drinking cup style in which truncated conical bands are related for extension and collapse. Some types of containers rely on manipulation of latches, etc. for achieving collapsed and extended positions, the aims being primarily to vary volume, conserve space, etc. One form of container with latchable walls is found in the U.S. Pat. No. 2,518,343, to Lindstrom which is in the form of a typical lunch box having variable-volume lower parts and a fixed-volume top part for carrying an insulated beverage container, for example. In that patent, rather complicated latch means is provided in connection with changing the volume of the lower parts. Further, this latch means is operative from within the box and thus interferes with packing and unpacking the box contents.
According to the present invention, a simplified construction is provided, including latch means operative from outside the container and cooperative interengageable lip means for defining stops regulating the extent of relative vertical movement between the upper and lower container parts. The latch means is of the bias-projectable type that can be forcibly overridden when changing from collapsed condition to extended condition, and which may be manually depressed to enable return to collapsed condition. A further object is to provide interfitting lips respectively on the movable parts, which engage to effect a substantial seal or seal-like relationship in the extended mode of the container.
Further features and advantages of the invention will appear as a preferred embodiment thereof is disclosed in detail in the ensuing description and accompanying sheet of drawings.